What is the correct form and technique for the single leg db deadlift in detail? I also want to know why one should do it in this way and not differently. What are common mistakes when doing this, why are they harmful and how to fix them.
If there are reasonable technique variations please also mention it and explain the how and why.
Over the web there you can see pictures of multiple different forms which makes you unsure whats correct and whats not. Take for example this picture:
You can see that the standing leg is slightly bend and that the arms are not perpendicular to the ground (as it would be the case in a normal deadlift). However perhaps this makes sense for the single leg deadlift, I don't know.
In the next picture the arms are perpendicular to the ground:
In the next picture only one dumbbell is used and the standing leg is straight:
However I also found images where the dumbbell is in the hand on the side of the standing leg:
I also found this variation which seems to be similar to the regular deadlift:
Is there a rough rule of thumb which gives a relation between the weight you can use in a regular deadlift and that one you can use in a db single leg deadlift?